This invention relates to gas fueled cooking appliances and more specifically to appliances with gas fueled surface heating units to be used in combination with a downdraft vent system.
Conventional downdraft venting system configurations with an exhaust air inlet located at cooktop level for removing combustion products and cooking vapors from the cooktop area work well with electric surface units. However, when used in combination with gas fueled surface units, the downdraft induced air flow at the cooktop surface tends to interfere with the gas flame. Examples of gas fueled appliances combining surface level downdraft venting with gas fueled surface units can be found in U.S. Pat. No. 4,413,610 to Berlik and U.S. Pat. No. 4,750,470 to Beach et al.
Beach et al describes a grill burner arrangement in which the grill burners are configured to provide greater heat output adjacent a side wall of the burner pan which is substantially opposite the air inlet of the downdraft ventilation system to compensate for the effects of the downdraft induced air flow on the performance of the grill burners. However, neither patent addresses surface heating unit problems caused by the downdraft induced surface level air flow.
In each of these examples, the surface heating units comprise standard gas burners which draw secondary air for the burners from the area beneath the cooking surface through an annular opening at the base of each burner. Spark ignition is provided by an ignition system disposed beneath the cooktop surface, using an igniter located relatively remotely from the burner ports and operatively coupled to the burners by flashtubes. In such arrangements the ignition system is relatively unaffected by the downdraft induced airflow in the vicinity of the burner. However, no provision is made in either example for automatic re-ignition of the burners.
Spark ignition systems are known in the art which do provide automatic re-ignition by detecting the absence of flame at the burner and respond by generating a spark to ignite the burner when the gas is initially turned on, and also to automatically re-ignite the burner in the event the flame goes out while the burner remains turned on. Examples of such automatic spark ignition systems can be found in U.S. Pat. Nos. 4,626,196 and 4,810,188. In such systems, the spark electrode also serves as a flame sensor. The circuitry is arranged such that when the burner is turned on, the ignition system generates a spark whenever flame is absent from the vicinity of the spark gap. It may be desirable to locate the electrode at the periphery of the burner proximate a burner port and hence exposed to the downdraft induced air flow.
Such ignition systems work well when used with surface burners which are not used in combination with surface level downdraft vent systems. However, use of such ignition systems for burners used in combination with a downdraft ventilation system in which the air inlet is located at burner level, the air flow in the vicinity of the burners induced by the downdraft vent system, tends to pull the flame away from the igniter electrode, causing the igniter system to generate a spark unnecessarily. This can result in repetitive "nuisance sparking" when one or more surface burners are on simultaneously with the downdraft vent system blower. Though such sparking does not present a safety hazard or otherwise interfere with the operation of the heating units, it does cause an annoying popping noise.
It is therefore a primary object of the present invention to provide an improved gas fueled cooking appliance which includes surface heating units with automatic spark ignition for use in combination with a surface level downdraft vent arrangement which substantially eliminates nuisance sparking caused by downdraft induced air flow in the vicinity of the surface burners.